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(No Model.)

R. E. M. BAIN.

SHUTTER FOR PHOTOGRAPHIC CAMERAS.

UNITED STATES PATENT OFFICE.

ROBERT E. M. BAIN, OF ST'. LOUIS, MISSOURI.

SHUTTER FOR PHOTOGRAPHIC CAMERAS.

SPECIFICATION forming part of Letters Patent No. 404,37 5, dated June 4, 1889.

Application filed January 14, 1889i Serial No. 296,300, (No model.)

To aZZ whom it may concern:

Be it known that I, ROBERT E. M. BAIN, a citizen ot' the United States, residing at the city of St. Iiouis, State of Missouri, have invented a certain new and useful Improvement in Shutters for Photographic Cameras, of

which the following' is a full, clear, and exact description.

My invention relates to improved means of operating the shutters oi' photographic cameras, and is an improvement on my invention, for which I have obtained Letters Patent, dated September 97, ISST, No. 370,679, for improvement in shutters forphotographic cameras.

My invention has for its object to vary the speed of the shutters when opening and closing the camera-tube for instantaneous exposure.

As described in my said patent, the shutters swing past each other on their respectu ive pivots within a case surrounding the camera-tube, each shutter having a circular opening which coincides with that of the camera-tube when the shutters are at halfstroke. Each shutter is formed with a curved slot, through which passes the pivot-pin of the other shut-ter, and with a short straight slot. Through the last-named slots of the shutters and through vertical slots formed through the front and back of the casing passes a pin which is connected with the pneumatic motor, the whole operating so that on the full vertical movement of the pin in either direction the shutters are opened and closed to the camera-tube.

New my present invention consists in two (or more) springs having alterable tension or force and applied separately or collectively to the actuating-pin o1' the shutters, whereby the speed of the latter when opening and closing the camera-tube for instantaneous eX- posure may be varied at pleasure, combined with a spring-catch for holding and releasing the shutters.

On the accompanying drawings, Figure l represents afront elevation of a camera-tube and shutter-case with the shutters closed according to my invention; Fig. 2, a left-hand end view thereof, omitting the catches seen at the lower part of Fig. l, 3, a rear elevation; and Fig. 4, a similar view to Fig.'3, with the camera-tube open for time-exposure, like letters et' reference denoting like parts in all the iigures.

Referring to Fig. l, a a represent the shutters, having, respectively, the circular openings l) D', pivots c c, curved slots d d', and straight slots e c', all arranged, as shown by dotted lines, within the casiu g f, surrounding the camera-tube g, and operated, substantially as described in my said patent, by the pin t', which passes through the combined slots e e of the shutters CL of, and through the vertical slots 7L in the Vfront and back of the casingf, the pin in the present instance being iixed in a slide j, which is mounted between guides j on the front of the casing f.

Bearing upward against the pin t', and normally closing-the shutters a o. to the cameratnbe g, is the arm 7e of a spring 7s 7e', which passes spirally round a fulcrum-stud Z, fixed to the casingf, and thence by an arm 7o to a bar in, which is fixed to the casingf and formed on its upper edge with a series of notches l 2 3 4 5, (more or less,) in notch l of which the arm 7J of the spring t' kis shown locked.

Adjacent to, but shown out of contact with, the actuating-pin i is the arm ny of a second spring n n', which is of greater tension than the spring 7c 7u', and provided with fulcrum o and notched bar p, similar in all respects to the spring 7o 7o. By this arrangement, (the pin 't being previously pulled down against the pressure of the spring 7U' 71; by any suitable means in the operation of the shutters a c,) on releasing the pin rf, the shutters a c will be opened and closed in instantaneous succession by the upward pressure of the spring 7e 7c on the pin fr', and at a speed corresponding to the tension imparted to the spring 7a it" when its arm 7s is locked in notch l of the bar m.

By successively shitting the arm 7./ to the notches 2 S 4 5 of the bar m the tension of the spring k 7u and speed of the shutters a a will be correspondingly increased; or the arm 7c of the spring 7c, 7e may be thrown out of contact with the actuating-pin t' and the arm n of the spring n n engaged therewith, so that by shifting the arm a to notches 2 3 #t 5 of the bar p further variations in the speed IOO of the shutters@ a are obtained, owing to the diiference of strength between the springs 7c k and n n; or, again, the arms lo and n of the springs 7c 7c and n 'n' may be engaged collectively with the pin 1'-, and the arms 7c n alternately or simultaneously shifted along the notches of their respective bars m p, for producing still further variations in the speed of the shutters a 0f, this feature being of important advantage in taking instantaneous negatives.

q represents a lever-catch pivoted to the back of the casing f, and formed withahooked end q', having a bevel-shaped back, which is normally held across the path of the actuating-pin t' by a spring q2, connecting the leverq with the casing f, combined with a stop-pin Q3 on the casing, so that the pin z', when pulled downward along the slot h for making an instantaneous negative, forces back the catch q until clear of the hook q', when the latter is returned by the spring q2 and holds the pin c' in the closed position of the shutters a a', as seen in Fig. 3. For releasing the hook q from the pin 1'., the lever q is thrown over on its pivot by hand or other suitable means.

In making a time-exposure I use a stoplever r, pivoted to the casing f and formed at its end adjacent to the actuating-pin a' with a tooth or catch r, which, on the lever r being thrown over to a certain extent on its pivot, crosses the slot h and forms a stop to the pin i, as seen in Fig. 4, when the shutters d a are at half-stroke or the camera-tube g fully open.

The movement of the lever r on its pivot may be controlled by the stop-pin c, which projects through a slot r in the lever r, or by any other suitable provision therefor.

Iclaim as my invention- 1. In apparatus for opening and closing photographic-camera shutters, the combination of two springs having different tensions and means for altering the respective tensions of said springs, with a pin passing through the shutters and through slots in the shuttercasing, substantially as shown, and for the purpose described.

2. In apparatus for opening and closing photographic-camera shutters, the combination of two springs having different tensions, each of said springs passing spirally round a iiXed stud and engaging in either one of a series of notches formed in a fixed bar, with the pin passing through the shutters and through vertical slots in the shutter-casing, substantially as shown, and for the purpose described.

In testimony whereof I affix my signature, in presence of two witnesses, this 7th day of January, 1889.

ROBERT E. M. BAIN.

Witnesses:

S. L. SCHRADER, J. L. HoRNsBY. 

